Every computer-aided design system uses a Cartesian coordinate system as a means of positioning elements. The position of every element, relative to an origin or base point, is dictated by the X, Y and Z coordinate values. A common origin point is required in order to synchronise discipline-specific models referenced from within viewing and clash detection software.

The production of construction documentation often requires setting out coordinates to be provided for certain elements of the building. These coordinates are generally relative to the national grid coordinate system.